Modified nano-SiO₂/PU hydrophobic composite film prepared through in-situ coupling by KH550 for oil-water separation

In this study, hydrophobic polymer composite films based on polyurethane (PU) were prepared for oil-water separation. Hydrophilic fumed silica (nano-SiO₂) was introduced as reinforcing filler, and silane coupling agent (KH550) was used to crosslink PU with nano-SiO₂ in situ for enhancing the nano-SiO₂ dispersion in the films. The microscopic morphology, crystalline structure, and hydrophobic properties of the films were characterized by using scanning electron microscopy, X-ray diffraction, FTIR spectroscopy, water contact angle, and water absorption tests. The results showed that the hydrophobicity of the nano-SiO₂/PU composite films increased with the addition of nano-SiO₂. KH550 not only significantly promoted the crosslink action between PU and nano-SiO₂ but also enhanced the dispersion of nano-SiO₂ in the composite films. Moreover, the pore structure of the prepared films was changed with the addition of nano-SiO₂ and KH550, which greatly improved the hydrophobicity. The test results for oil-water separation performance showed that the prepared composite films can efficiently separate the oil from oil-water mixtures with good repeatability.